(a) Field of the Invention
The present invention relates to a fold-type data processing apparatus having a hinge and, more particularly, to a fold-type data processing apparatus, such as cellular phone, hand-held personal computer and portable data assistant, having a hinge mechanism therein.
(b) Description of the Related Art
Recent cellular phones have a variety of functions in addition to the conventional telephone function, such as internet browser, e-mail and schedule management functions. Thus, the cellular phone may be referred to as a portable data processing apparatus or personal data assistant. This fact necessitates the cellular phone to have a larger-size display unit to display thereon a larger amount of image information including figures as well as characters and numerals.
To solve a trade-off between a larger-size screen for the display unit and a smaller weight of the cellular phone as encountered in the conventional technique, a fold-type structure is increasingly used for the chassis of the cellular phone. In general, the fold-type structure of the cellular phone is such that the chassis of the cellular phone has a top chassis section (top unit) and a bottom chassis section (bottom unit) coupled together via a hinge, and the display unit and the keyboard are exposed for operation by unfolding the top chassis section with respect to the bottom chassis section. A fold-type structure has been proposed wherein the screen of the display unit is exposed in a folded position of the chassis for allowing the cellular phone to function as an e-mail or browser unit without switch-ON of the telephone function.
JP Patent Publication 11(1999)-215218 (first publication) describes a fold-type structure of the cellular phone wherein the top chassis section mounting thereon a display unit and the bottom chassis section mounting thereon a keyboard are coupled together via a ball joint for allowing swiveling of the top chassis section in any direction with respect to the bottom chassis section.
In the fold-type structure described in the first publication, it is difficult to fix the relative attitude of the top chassis section with respect to the bottom chassis section during an unfolded position thereof, because both the sections are coupled via the ball joint. This rather hinders the user from handling the cellular phone comfortably.
JP Patent Publication 2002-158758 (second publication) describes a fold-type structure of the cellular phone, wherein the top chassis section mounting thereon a display unit and the bottom chassis section mounting thereon a keyboard are coupled together for allowing swiveling of the top chassis section with respect to the bottom chassis section so that the operating planes of the display unit and the keyboard are directed in the same direction.
In the fold-type structure described in the second publication, if one of the chassis sections is swiveled with respect to the other, with surface portions of both the chassis sections being in contact with one another, the contacted surface portions may have mechanical damages thereon. This problem is common to the fold-type structure described in the first publication.